Here is the preferred way to export models from SketchUp in STL format:
You will need an STL “exporter” plug in for SketchUp. Here is a link to a free exporter: http://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl . This nifty little plugin will enable you to export your model in STL format. At this site you can download the plugin and read up on the documentation. It is also compatible with: SkeinForge, FreeMill, Vectric Cut-3D, Roland Modela Player, Boxford’s 3D GeoCAM, Carvewright Designer software, DeskProtoLite, MeshCAM Art, Art Cam.
1. Install the plugin, using the installation instruction provided on the site.
2. After you have installed the plugin, reopen SketchUp and select the object to be 3D printed (by triple clicking or what ever method you prefer, so long as the entire object is highlighted in blue).
3. Click on the drop down menu for “TOOLS” and select “EXPORT TO DXF OR STL”
4. Select export unit as “MILLIMETERS”
5. Select “stl”
6. When the save file name window opens and you type in the name – be sure to type the extension “.stl” to the end of the name. This may not be necessary depending on what version you have.
7. After it has saved the STL file, you will see a window pop up like this.
Congratulations, you have just saved your first STL file! Now, before you slice the STL file into gCode, let’s make sure it is watertight by using MeshLab.